Essential Sustainability Technical Knowledge

 

You don't need to be a sustainability expert, but you do need solid fundamentals. Here's what interviewers expect you to know.

 

Carbon Accounting Basics

 

Understand the three scopes of emissions:

 

• Scope 1: Direct emissions from company-owned sources. Think combustion in boilers, company vehicles, or industrial processes

 

• Scope 2: Indirect emissions from purchased electricity, steam, heating, or cooling

 

• Scope 3: All other indirect emissions in the value chain. This includes purchased goods, business travel, employee commuting, product use, and end-of-life treatment

 

Know that Scope 3 is usually 70-90% of a company's total footprint but also the hardest to measure and control.

 

Common Sustainability Metrics and Units

 

You'll work with these units regularly:

 

• Tons of CO2 equivalent (tCO2e): Standard measure that converts all greenhouse gases to CO2 equivalents

 

• Carbon intensity: Emissions per unit of output (like tCO2e per ton of product)

 

• Energy intensity: Energy use per unit of output

 

• Water intensity: Water consumption per unit of output

 

Renewable Energy Economics

 

Understand the basics of how different technologies compare:

 

• Solar and wind are now the cheapest electricity sources in most markets

 

• Levelized Cost of Energy (LCOE) measures total lifetime cost per unit of energy produced

 

• Capacity factor matters - solar and wind don't produce 24/7

 

• Battery storage is becoming economical for 4-8 hour storage

 

• Green hydrogen shows promise but is still expensive

 

Circular Economy Concepts

 

Know these key principles:

 

• Design out waste from the start

 

• Keep products and materials in use

 

• Regenerate natural systems

 

You should understand the difference between recycling (breaking materials down) and reuse or remanufacturing (keeping products intact).

 

Sustainability Case Interview Frameworks

 

Creating frameworks for sustainability cases follows the same process as traditional cases. Here are some common buckets you may need to include in your sustainability case interview framework.

 

Environmental Impact

 

• Carbon emissions across all scopes

 

• Energy and water use

 

• Waste generation and circularity

 

• Biodiversity and land use

 

• Air and water pollution

 

Financial Analysis

 

• Upfront capital costs

 

• Operating cost changes

 

• Revenue impacts

 

• Payback period and NPV

 

• Cost of carbon

 

Technical Feasibility

 

• Technology maturity and availability

 

• Infrastructure requirements

 

• Scalability

 

• Timeline and phasing

 

• Technical risks

 

Stakeholder Considerations

 

• Regulatory requirements and compliance

 

• Investor and lender expectations

 

• Customer preferences and willingness to pay

 

• Employee engagement

 

• Community impact

 

• NGO and activist concerns

 

Strategic Fit

 

How does this align with the broader business?

 

• Consistency with corporate strategy

 

• Brand and reputation effects

 

• Competitive positioning

 

• Risk mitigation

 

• Future-proofing against regulation

 

Here's an example framework for a carbon reduction case:

 

Objective: Reduce emissions 40% by 2030 while maintaining profitability

 

1. Current State

 

• Emissions baseline by scope

 

• Current initiatives and trajectory

 

• Cost structure

 

2. Reduction Options

 

• Energy efficiency improvements

 

• Renewable energy procurement

 

• Process changes

 

• Supply chain interventions

 

• Offsets or removals

 

3. Evaluation Criteria

 

• Cost per ton CO2 reduced

 

• Capital requirements

 

• Implementation timeline

 

• Technical risk

 

• Co-benefits

 

4. Implementation

 

• Sequencing and priorities

 

• Organizational changes needed

 

• Measurement and tracking

 

Solving Quantitative Problems in Your Sustainability Case Interview

 

Sustainability cases involve specific types of math. Here are the most common calculations you'll do.

 

1. Carbon Reduction Calculations

 

You'll often compare different reduction options by calculating tons of CO2 saved and cost per ton.

 

Example: A factory uses 100,000 MWh of electricity per year from the grid at an emission factor of 0.5 tCO2/MWh. They're considering three options:

 

• Option A: Switch to renewable energy. Costs $2M upfront, saves $500K/year on electricity

 

• Option B: Improve efficiency 20%. Costs $3M upfront, reduces electricity use to 80,000 MWh

 

• Option C: On-site solar for 30% of use. Costs $5M upfront, generates 30,000 MWh/year

 

Calculate emissions reduced and cost per ton for each option.

 

• Current emissions: 100,000 MWh × 0.5 tCO2/MWh = 50,000 tCO2/year

 

• Option A: Reduces all emissions = 50,000 tCO2/year saved. Net cost over 10 years = $2M - ($500K × 10) = -$3M (saves money). Cost per ton = -$3M / (50,000 × 10) = -$6/ton

 

• Option B: Reduces 20,000 MWh = 10,000 tCO2/year saved. Cost = $3M. Cost per ton = $3M / (10,000 × 10) = $30/ton

 

• Option C: Reduces 30,000 MWh = 15,000 tCO2/year saved. Cost = $5M. Cost per ton = $5M / (15,000 × 10) = $33/ton

 

Option A is clearly best if you can secure renewable energy contracts.

 

2. LCOE Calculations

 

Levelized cost of energy measures the total cost per unit of energy over a project's lifetime.

The formula is: LCOE = (Total lifetime costs) / (Total lifetime energy production)

 

Example: A solar project costs $10M upfront and $200K/year to operate. It produces 5,000 MWh/year for 25 years.

 

• Total costs = $10M + ($200K × 25) = $15M

 

• Total production = 5,000 MWh × 25 = 125,000 MWh

 

• LCOE = $15M / 125,000 MWh = $120/MWh

 

Compare this to current electricity costs to determine if it makes sense.

 

3. Payback Period

 

Payback period measures how long until an investment pays for itself?

 

Example: Switching to LED lighting costs $500K upfront and saves $100K/year in electricity costs.

 

Payback period = $500K / $100K = 5 years

 

In sustainability cases, also calculate the "carbon payback" - how long until emissions savings offset any emissions from manufacturing or installation.

 

4. Material Flow Analysis

 

For circular economy cases, you’ll need to use math to track materials through the system.

 

Example: A company produces 10,000 tons of product per year. Currently, 20% is made from recycled content. They want to reach 50% recycled content.

 

• Current recycled input = 10,000 × 20% = 2,000 tons

 

• Target recycled input = 10,000 × 50% = 5,000 tons

 

• Additional recycled material needed = 5,000 - 2,000 = 3,000 tons

 

Then calculate collection rates, sorting efficiency, and reprocessing costs to determine feasibility.